A switch for high voltage responsible for interrupting a fault current has to satisfy the following two items when interrupting the current.
One is to surely extinguish, in a very short time, an arc generated between contacts after the opening. The other is to prevent dielectric breakdown when a transient recovery voltage rapidly rises between the contacts after the arc extinction.
In recent years, there has been widely adopted a puffer switch of a type in which one circuit breaker part having connectable/separable contacts are housed in a pressure vessel in which SF6 gas as insulating gas is sealed, and the insulating gas is sprayed to the contacts at the time of an interrupting operation, to extinguish an arc.
In this type, the aforesaid two items have to be achieved with a single circuit breaker.
On the other hand, there has also been developed a switch of a type that achieves the interruption of the fault current by connecting circuit breaker parts each specialized in satisfying one of the aforesaid two items.
That is, this is a switch of a type having the plural circuit breaker parts and assigning the roles separately to the respective circuit breaker parts.
Such a switch is formed by separating an inner space of a pressure vessel, housing the circuit breaker part excellent in arc extinction performance and the circuit breaker part excellent in insulation performance in the one and other parts of the space respectively, and electrically connecting the both in series.
In the above-described circuit breaker parts, when the circuit breaker parts are simply opened at the time of current interruption, a transient recovery voltage according to electrostatic capacitance of each of the circuit breaker parts is applied between contacts of the circuit breaker parts after the arc extinction.
Therefore, insulation performance of the switch depends on insulation performance of the circuit breaker part poorer in insulation performance, so that the original object to assign the roles separately to the respective circuit breaker parts cannot be achieved.
A switch according to this embodiment has an object to provide a switch which is capable of easily achieving an interruption duty required for a high-voltage switch and whose interruption time is short.